I've seen replacement kits for DMF clutches. It's a normal clutch kit plus new flywhee.l IIRC it's been around 350 € when I looked for my Twinair. Luckily my car was not equipped with DMF
I can understand an independent garage not knowing this when they first quoted for the job, but not realising once they'd got the gearbox off and the clutch out....
Hope they gave you a good deal on the labour costs second time around - or did you take it somewhere else?